/Engine/Source/Runtime/Engine/Public/UnrealClient.h
Returns all actors and models found in the hit proxy within a specified region. InRect must be entirely within the viewport's client area. If the hit proxies are not cached, this will call ViewportClient->Draw with a hit-testing canvas.
void GetActorsAndModelsInHitProxy ( FIntRect InRect, [TSet](API\Runtime\Core\Containers\TSet)< [AActor](API\Runtime\Engine\GameFramework\AActor) * > & OutActors, [TSet](API\Runtime\Core\Containers\TSet)< [UModel](API\Runtime\Engine\UModel) * > & OutModels )